 var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
            var base64DecodeChars = new Array(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                                              -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                                              -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57,
                                              58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0,  1,  2,  3,  4,  5,  6,
                                              7,  8,  9,  10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
                                              25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
                                              37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1,
                                              -1, -1);

            function base64encode(str)
                {
                var out, i, len;
                var c1, c2, c3;
                len = str.length;
                i = 0;
                out = "";

                while (i < len)
                    {
                    c1 = str.charCodeAt(i++) & 0xff;

                    if (i == len)
                        {
                        out += base64EncodeChars.charAt(c1 >> 2);
                        out += base64EncodeChars.charAt((c1 & 0x3) << 4);
                        out += "==";
                        break
                        }

                    c2 = str.charCodeAt(i++);

                    if (i == len)
                        {
                        out += base64EncodeChars.charAt(c1 >> 2);
                        out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
                        out += base64EncodeChars.charAt((c2 & 0xF) << 2);
                        out += "=";
                        break
                        }

                    c3 = str.charCodeAt(i++);
                    out += base64EncodeChars.charAt(c1 >> 2);
                    out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
                    out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
                    out += base64EncodeChars.charAt(c3 & 0x3F)
                    }

                return out
                }

            function base64decode(str)
                {
                var c1, c2, c3, c4;
                var i, len, out;
                len = str.length;
                i = 0;
                out = "";

                while (i < len)
                    {
                    do
                        {
                        c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff]
                        } while (i < len && c1 == -1);

                    if (c1 == -1)
                        break;

                    do
                        {
                        c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff]
                        } while (i < len && c2 == -1);

                    if (c2 == -1)
                        break;

                    out += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));

                    do
                        {
                        c3 = str.charCodeAt(i++) & 0xff;

                        if (c3 == 61)
                            return out;

                        c3 = base64DecodeChars[c3]
                        } while (i < len && c3 == -1);

                    if (c3 == -1)
                        break;

                    out += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));

                    do
                        {
                        c4 = str.charCodeAt(i++) & 0xff;

                        if (c4 == 61)
                            return out;

                        c4 = base64DecodeChars[c4]
                        } while (i < len && c4 == -1);

                    if (c4 == -1)
                        break;

                    out += String.fromCharCode(((c3 & 0x03) << 6) | c4)
                    }

                return out
                }